Mc. Sekar et al., DISSOCIATION OF CYCLIC INOSITOL PHOSPHOHYDROLASE ACTIVITY FROM ANNEXIN-III, The Journal of biological chemistry, 271(14), 1996, pp. 8295-8299
Cyclic inositol phosphohydrolase is a phosphodiesterase that cleaves t
he cyclic bond of cyclic inositol monophosphate, In 1990, Boss ct at (
Boss, T. S., Tait, J. F., and Majerus, P. W. (1990) Science 248, 605-6
07) purified this enzyme from human placenta and reported that cyclic
inositol phosphohydrolase is identical to annexin III, Independent con
firmation of this finding has not been provided. The relative distribu
tion of annexin III and cyclic inositol phosphohydrolase activity in r
at kidney and spleen indicated that annexin III can be dissociated hom
cyclic inositol phosphohydrolase activity, Rat spleen contains large
quantities of annexin III, but has very little cyclic inositol phospho
hydrolase activity, In contrast, rat kidney, one of the richest source
s of cyclic inositol phosphohydrolase activity, possesses very little
(immunohistochemistry) or no (Western blot) annexin IIIm. similar to c
ytosol of human placenta, cytosol of guinea pig kidney contains both a
nnexin III and cyclic inositol phosphohydrolase. On SDS-gel electropho
resis, guinea pig kidney annexin III has a slightly different mobility
than the human placental annexin III. Human placental annexin III co-
migrates with cyclic inositol phosphohydrolase on ion exchange chromat
ography, while guinea pig kidney annexin III is clearly dissociated fr
om cyclic inositol phosphohydrolase on ion exchange chromatography. Bo
th guinea pig kidney annexin III and human placental annexin III pelle
t with the addition of calcium and centrifugation, while cyclic inosit
ol phosphohydrolase activity in both of these tissues remains in the s
upernatant. Our studies clearly show that cyclic inositol phosphohydro
lase and annexin III are two different proteins.